Hotspots of annual fish along the Patos-Mirim Lagoon System and adjacent areas in Southern Brazil,with an evaluation of conservation priority for species and localities

Biodiversity and Conservation - Rivulidae represents one of the most endangered taxa in Brazil. This family encompasses species known as annual or seasonal fish because they possess unique...     

Linking Microbial Community and Catabolic Gene Structures during the Adaptation of Three Contaminated Soils under Continuous Long-Term Pollutant Stress

Three types of contaminated soil from three geographically different areas were subjected to a constant supply of benzene or benzene/toluene/ethylbenzene/xylenes (BTEX) for a period of 3 months. Different from the soil from Brazil (BRA) and Switzerland (SUI), the Czech Republic (CZE) soil which was previously subjected to intensive in situ bioremediation displayed only negligible changes in community structure. BRA and SUI soil samples showed a clear succession of phylotypes. A rapid response to benzene stress was observed, whereas the response to BTEX pollution was significantly slower. After extended incubation, actinobacterial phylotypes increased in relative abundance, indicating their superior fitness to pollution stress. Commonalities but also differences in the phylotypes were observed. Catabolic gene surveys confirmed the enrichment of actinobacteria by identifying the increase of actinobacterial genes involved in the degradation of pollutants. Proteobacterial phylotypes increased in relative abundance in SUI microcosms after short-term stress with benzene, and catabolic gene surveys indicated enriched metabolic routes. Interestingly, CZE soil, despite staying constant in community structure, showed a change in the catabolic gene structure. This indicates that a highly adapted community, which had to adjust its gene pool to meet novel challenges, has been enriched.     

Indirect effect of elevated CO2 concentration on Bemisia tabaci MEAM1 feeding on Bt soybean plants

The development of herbivore insects is influenced by the quality of their host plants. Elevated CO₂ alters plant metabolism, which may change the nutritional quality of the plant, modifying the life history and feeding behaviour of herbivore insects. Understanding how insect pests respond to increasing CO₂ concentration is essential for predicting the impact of the pest on food security. In this study, we investigated the effects of elevated CO₂ (eCO₂) on the life history and feeding behaviour of the MEAM1 species of Bemisia tabaci on a Bt soybean cultivar. We found that eCO₂ increased the egg to adult development time and reduced the reproductive responses (fecundity and fertility) of B. tabaci. The whitefly B. tabaci that fed on the soybean plants grown under eCO₂ conditions was negatively influenced by several traits related to the host plant resistance, such as the time spent on phloem sap ingestion. Furthermore, we evaluated the changes in the C:N concentration and plant morphology of the Bt plants. The biomass (weight of leaves and stems) of the Bt soybean plants grown under eCO₂ conditions was significantly increased, and the elevated C:N ratio in the phenological stage V6 (i.e. when the plants had six trifoliate leaves developed) was the most pronounced difference in the Bt soybean plants subjected to eCO₂ treatment. Taken together, our results indicate that Bt plants cultivated under eCO₂ inhibit B. tabaci feeding, which can reduce whitefly infestations of the soybean fields.     

A multilocus perspective on the phylogenetic relationships and diversification of rodents of the tribe Abrotrichini (Cricetidae: Sigmodontinae)

Abrotrichini is a recently defined and diagnosed tribe of Sigmodontinae with a complex taxonomy. Abrotrichine genera, Abrothrix (including Chroeomys), Chelemys, Geoxus, Notiomys and Pearsonomys, are mostly distributed in the central and southern Andes and adjacent lowlands and show terrestrial and fossorial habits. Recent studies have evidenced some incongruence between current taxonomy and abrotrichine phylogeny, such as the polyphyly of Chelemys and paraphyly of Geoxus respect to Pearsonomys. We used DNA sequence data of six loci (one mitochondrial and five nuclear) to resolve the relationships within the tribe. Independent and combined analyses of these loci were carried out using parsimony, maximum likelihood and Bayesian inference. Estimates of divergence time of the main lineages of abrotrichines were calculated with a molecular clock using as calibration, a fossil recently found. The concatenated data set increased the resolution and defined the relationships within the tribe. Our phylogenetic analyses corroborate that Abrothrix is sister of a clade containing the long‐clawed abrotrichines. We recovered two main clades within Abrothrix that match morphologic variation and geographic distribution of its species. In addition, we corroborated the lack of monophyly of Chelemys and the lack of monophyly of Geoxus. We discuss different taxonomic scenarios to abrotrichine classification reflects the phylogenetic relationships obtained in this study. Our molecular clock estimated the Abrotrichini crown age to be around the early Pliocene (4.4 Ma) and suggest that the tribe diversified over a short period of time.